runtime/cgo: linux/arm64 cgo support

Change-Id: I309e3df7608b9eef9339196fdc50dedf5f9439f2
Reviewed-on: https://go-review.googlesource.com/8439Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>

src/runtime/cgo/asm_arm64.s

+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+/*
+ * void crosscall2(void (*fn)(void*, int32), void*, int32)
+ * Save registers and call fn with two arguments.
+ */
+TEXT crosscall2(SB),NOSPLIT,$-8
+	/*
+	 * We still need to save all callee save register as before, and then
+	 *  push 2 args for fn (R1 and R2).
+	 * Also note that at procedure entry in 7g world, 8(RSP) will be the
+	 *  first arg.
+	 * TODO(minux): use LDP/STP here if it matters.
+	 */
+	SUB	$128, RSP
+	MOVD	R1, (8*1)(RSP)
+	MOVD	R2, (8*2)(RSP)
+	MOVD	R19, (8*3)(RSP)
+	MOVD	R20, (8*4)(RSP)
+	MOVD	R21, (8*5)(RSP)
+	MOVD	R22, (8*6)(RSP)
+	MOVD	R23, (8*7)(RSP)
+	MOVD	R24, (8*8)(RSP)
+	MOVD	R25, (8*9)(RSP)
+	MOVD	R26, (8*10)(RSP)
+	MOVD	R27, (8*11)(RSP)
+	MOVD	g, (8*12)(RSP)
+	MOVD	R29, (8*13)(RSP)
+	MOVD	R30, (8*14)(RSP)
+
+	MOVD	R0, R19
+
+	// Initialize Go ABI environment
+	BL      runtime·reginit(SB)
+	BL	runtime·load_g(SB)
+	BL	(R19)
+
+	MOVD	(8*1)(RSP), R1
+	MOVD	(8*2)(RSP), R2
+	MOVD	(8*3)(RSP), R19
+	MOVD	(8*4)(RSP), R20
+	MOVD	(8*5)(RSP), R21
+	MOVD	(8*6)(RSP), R22
+	MOVD	(8*7)(RSP), R23
+	MOVD	(8*8)(RSP), R24
+	MOVD	(8*9)(RSP), R25
+	MOVD	(8*10)(RSP), R26
+	MOVD	(8*11)(RSP), R27
+	MOVD	(8*12)(RSP), g
+	MOVD	(8*13)(RSP), R29
+	MOVD	(8*14)(RSP), R30
+	ADD	$128, RSP
+	RET

src/runtime/cgo/gcc_arm64.S

+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+ * Apple still insists on underscore prefixes for C function names.
+ */
+#if defined(__APPLE__)
+#define EXT(s) _##s
+#else
+#define EXT(s) s
+#endif
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void *g), void *g)
+ *
+ * Calling into the 7g tool chain, where all registers are caller save.
+ * Called from standard ARM EABI, where x19-x29 are callee-save, so they
+ * must be saved explicitly, along with x30 (LR).
+ */
+.globl EXT(crosscall1)
+EXT(crosscall1):
+	stp x19, x20, [sp, #-16]!
+	stp x21, x22, [sp, #-16]!
+	stp x23, x24, [sp, #-16]!
+	stp x25, x26, [sp, #-16]!
+	stp x27, x28, [sp, #-16]!
+	stp x29, x30, [sp, #-16]!
+	mov x29, sp
+
+	mov x19, x0
+	mov x20, x1
+	mov x0, x2
+
+	blr x20
+	blr x19
+
+	ldp x29, x30, [sp], #16
+	ldp x27, x28, [sp], #16
+	ldp x25, x26, [sp], #16
+	ldp x23, x24, [sp], #16
+	ldp x21, x22, [sp], #16
+	ldp x19, x20, [sp], #16
+	ret
+
+.globl EXT(__stack_chk_fail_local)
+EXT(__stack_chk_fail_local):
+1:
+	b 1b
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_linux_arm64.c

+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include <string.h>
+#include <signal.h>
+#include "libcgo.h"
+
+static void *threadentry(void*);
+
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase);
+void (*setg_gcc)(void*);
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	// Not sure why the memset is necessary here,
+	// but without it, we get a bogus stack size
+	// out of pthread_attr_getstacksize.  C'est la Linux.
+	memset(&attr, 0, sizeof attr);
+	pthread_attr_init(&attr);
+	size = 0;
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
+	ts->g->stackhi = size;
+	err = pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
+{
+	pthread_attr_t attr;
+	size_t size;
+
+	setg_gcc = setg;
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	g->stacklo = (uintptr)&attr - size + 4096;
+	pthread_attr_destroy(&attr);
+
+	if (x_cgo_inittls) {
+		x_cgo_inittls(tlsg, tlsbase);
+	}
+}